Thermionic valve oscillator arrangement



April 25, 1939.

D. F. GEORGE 2,155,6 9

THERMIONIC VALVE OSCILLATOR ARRANGEMENT Filed Jan. 25, 1936 70 M45751? 501/1962 0F //.F. OSC.

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nu I "v INVEXTOR. DOUGLAS F. GEORGE ATTORNEY.

Patented Apr. 25, 1939 UNITED STATES PATENT OFFICE THERMIONIC VALVE OSCILLATOR ARRANGED/TENT Application January 25, 1936, Serial No. 60,786 In Great Britain March 18, 1935 10 Claims.

This invention relates to electron discharge device oscillator arrangements and has for its object to provide an oscillator arrangement whereby an oscillator capable of providing oscillatory output of relatively high power may be controlled in frequency by input oscillations of relatively low power and constant or predetermined frequency.

According to this invention a thermionic valve oscillator arrangement comprises in combination 3.1) a multi-grid thermionic valve oscillator employing reaction, a master source of controlling oscillations and means for applying oscillatory energy from said master source to one of the grids of said multi-grid valve oscillator, said one grid being a grid other than that which functions in the selfoscillating process of the multi-grid oscillator.

Preferably, means are provided whereby reaction upon said one grid is reduced or substantially eliminated. The said means for preventing reac- 29 tion upon the frequency controlling grid of the multi-grid oscillator preferably includes an isolator thermionic valve stage interposed between the master source and the said grid.

The invention is illustrated in the accompanying drawing wherein Figs. 1 to 3 show diagrammatically three embodiments thereof.

In the embodiment shown in Fig. 1, a multigrid valve oscillator constituted by a screen grid valve I of fairly high power is employed, said in valve having a tuned or band pass output circuit associated with its anode 2 and outer grid 3. As shown, there is a tuned circuit constituted by a main inductance i in series with a small output coupling inductance 5, the two inductances 4, 5

:15 being shunted by a tuning condenser 6. One terminal of the tuning condenser 6 is capacity cou pled by a condenser 'I to the anode 2 and the other terminal thereof is capacity coupled by a condenser 8 to the screen grid 3. The said screen 49 grid 3 is connected through a grid resistance or leak 9 to the cathode point of the valve, e. g., in the case of a valve having a filament I ll heated by alternating current to the electrical center II of a resistance l2 connected across the said fila- 45 ment. The said screen grid 3 is connected through a high frequency choke I3 to a suitable point It upon the potentiometer I5, one end of which connected to the positive terminal I6 of a source of anode potential (not shown) and the 50 other end of which is connected to the cathode point I I. The anode 2 of the screen grid valve I is connected to the positive terminal I6 of the source of anode potential through a high fre quency choke I1.

55 All the apparatus so far described (except the small coupling inductance 5) is enclosed within screening I8 and the said coupling inductance 5 which is outside the said screening is coupled to the inductance I9 in an output parallel tuned circuit I9, 253, which together with coupling induc- 5 tance 5 and the tuned circuit in which it is connected, constitute a band pass filter of desired predetermined width. It is to be understood, of course, that the invention is not limited to the particular type of band pass filter illustrated and any other band pass arrangement may be used.

The inner or control grid 2| of the screen grid valve I is connected through a suitable grid leak resistance 22 to the cathode point I I thereof and is also capacity coupled by a condenser 23 to the anode 2 1 of an isolator valve 25 which in the present example is constituted by a pentode, and the said anode 24 is connected through a high frequency choke 25 to the positive terminal I6 of the source of anode potential. The outermost or suppressor grid 2i of the pentode 25 is connected either inside or outside the valve envelope to the cathode 28 thereof and to the cathode heater point 33; the middle grid 29 of the pentode is connected to the positive terminal I8 through a suitable voltage dropping resistance 30 and the innermost grid 3! of the pentode is connected at terminal 32 to a master source (not shown) of high frequency oscillations which is preferably of frequency near the middle of the pass band of the band pass filter. It is, however, possible to employ a master source whose frequency is harmonically or sub-harmonically related to a frequency in the pass band so that frequency changing action will also take place in the screen grid oscillator valve. The cathode heater point 33 of the pentode valve is connected to the cathode point II of the screen grid valve I and the said pentode valve and its associated circuit elements are also enclosed in screening 3%. Preferably, in practice, separate screening boxes are not used but instead as shown there is a unitary screening arrangement with screening partitions between the isolator valve and the master source on the one hand and the screen grid valve on the other, there being also a partition between the screen grid valve and the output tuned or other circuit Ill, "2d. The master source may be any suitable oscillator of relatively small power, for example, a piezo electric crystal oscillator.

In the modification shown in Fig. 2, the isolator valve 25 of Fig. l is dispensed with and reaction upon the frequency controlling or inner grid 2| of the multi-grid oscillator prevented by constituting the said multi-grid oscillator by a pentode 55 valve I having a screen grid 35 between that grid 2| to which the master or controlling oscillations are applied (via terminal 32 and across resistance 38) and that grid 3 which functions in the self-oscillating action of the multi-grid valve. The screen grid 35 is' suitably biased positively Via lead 35a and is connected to the cathode point as respects operating frequencies through condenser 35b. In Fig. 2 the output circuit of the valve I is arranged similarly to that of the oscillator valve in Fig. 3 (to be described below) and, as in Fig. 1, the broken lines represent screening.

In a still further modification illustrated in Fig. 3, a screen grid valve I is again used as the multigrid main oscillator. In Fig. 3 the screen grid valve I has its anode 2 connected to one end of a parallel tuned circuit 4, 6, the other end of which is connected through 'a condenser shunted grid leak resistance combination 8, 9 to the screen grid 3. A tap 36 upon the coil 4 in the said parallel tuned circuit 4, 6 is connected through a suitable condenser 31 tothe cathode point ll of the screen grid valve and the load (represented as a resistance 20a) for the said screen grid valve oscillator is so connected that the equivalent load impedance is in shunt between said tap 36 and the anode 2, anode potential being applied via said tap from terminal [6a. The inner or control grid 2] of the screen grid valve is connected to the cathode point through a suitable grid resistance 38 and is also coupled through a condenser 39 to the anode 40 of a piezo-electrically controlled relatively low power oscillator constituted by a second screen grid valve 4|. The anode 4B of the second screen grid valve is connected to the inner grid 42 thereof through a condenser 44 and a piezo-electric crystal 45 in series and is also connected through a choke 43 and terminal IE to a suitable anode potential source (not shown). The grid 42' is connected to the cathode point H (which is common for both screen grid valves I and 4|) through a resistance 46 and the terminal I6 is connected to point H through two resistances 41, 48 in series, the point between them being connected to the outer or screen grid 49 of the screen grid valve 41. The two valves are screened from one another; for example, as illustrated, they may be housed in a screening box (represented by broken lines) which has a partition on one side of which is the second screen grid valve 4i and its circuit elements (in cluding the coupling condenser 39 and coupling resistance 38), the first screen grid valve l and its circuit elements being on the other side or said partition.

By virtue of the high amplification effects obtained in an oscillator arrangement in accordance with this invention, it is possible to utilize a master oscillator source of quite small power to maintain a much more powerful oscillator in step over a reasonably large range of frequencies even though quite large amounts of oscillatory power be taken from said larger oscillator.

Though not limited to its application thereto, the invention is of considerable advantage as applied to aircraft, portable and other compact transmitters where-saving of weight and space is an important consideration.

What is claimed is:

l. A regenerative electron discharge device oscillation generation system comprising an electron discharge device oscillator having an anode, cathode, control grid and screen grid, means for maintaining said control grid at an average negative potential and'said screen grid at an average positive potential relative to said cathode, a feedback path including an oscillation circuit extending from said anode to said screen grid, a connection from an intermediate point on said oscillation circuit to said cathode, a non-oscillating electron discharge device amplifier having input and output electrodes, a capacitive connection from said output electrode to the control grid of said oscillator, and a connection from said input electrode to a master oscillator of low power and constant frequency.

2. An oscillation generator arrangement comprising an electron discharge device oscillator having an anode, a cathode, a control grid and a screen grid, means for maintaining said control grid at an average negative potential and said screen grid at an average positive potential relative to said cathode, an oscillatory circuit comprising a pair of inductance coils and a condenser in shunt of said coils, a connection from the junction point of said coils to said cathode, a capacitor connected between one plate of said condenser and said anode, and another capacitor connected between another plate of said condenser and said screen grid, an output circuit coupled to one of said coils, a non-oscillating electron discharge device amplifier having an input electrode and an 'output electrode, a capacitive path between said output electrode and the control grid of said first device, and a source of low power constant frequency oscillations coupled to the input electrode of said amplifier device.

3. An oscillation generator arrangement comprising an electron discharge device oscillator having an anode, a cathode, a control grid and a screen grid; means for maintaining said control grid at an average negative potential and said screen grid at an average positive potential relative to said cathode; an oscillatory circuit comprising a pair of inductance coils and a condenser in shunt to said coils; a connection from the junction point of said coils to said cathode; a capacitor connected between one plate of said condenser and said anode, and another capacitor connected between another plate of. said condenser and said screen grid, an output circuit coupled to one of said coils; a non-oscillating electron discharge device amplifier having an input electrode and an output electrode, a capacitive path between said output electrode and the control grid of said first device, a source of low power constant frequency oscillations coupled to the input electrode of said amplifier device; and means for screening said first device fromv said second device and from that coil which is coupled to said output circuit, and said second device from said source of constant frequency oscillations.

4. An oscillation generator arrangement comprising an electron discharge device oscillator having an anode, a cathode, a control grid and a screen grid, means for maintaining said control grid at an average negative potential and said screen grid at an average positive potential relative to said cathode, an oscillatory circuit comprising a pair of inductance coils and a condenser in shunt with said coils coupled between said anode and said screen grid, a connection from an intermediate point on said oscillatory circuit to said cathode, means for supplying low power constant frequency oscillations to said other grid, and a parallel tuned circuit coupled to one of said coils of said pair, which together with said one coil constitutes a band pass filter.

5. A regenerative oscillation generator ar- 'r'angernent comprising an electron discharge device oscillator having an anode, a cathode, a control grid and a screen grid, means for maintaining said control grid at an average negative potential and said screen grid at an average positive potential relative to said cathode, an oscillatory circuit comprising a pair of inductance coils and a condenser in shunt with said coils coupled between said anode and said screen grid, a connection from an intermediate point on said oscillatory circuit to said cathode, means for supplying low power constant frequency oscillations to said other grid, and a load circuit coupled to one of said coils of said pair, said load together with said one coil constituting a band pass filter.

6. An oscillation generator arrangement comprising an electron discharge device oscillator having an anode, a cathode, a control grid and a screen grid; means for maintaining said control grid at an average negative potential and said screen grid at an average positive potential relative to said cathode; an oscillatory circuit comprising a pair of inductance coils and a condenser in shunt with said coils coupled between said anode and one of said grids; means for supplying low power constant frequency oscillations to said other grid; a load circuit coupled to one of said coils of said pair, said load together with said one coil constituting a band pass filter; and shielding screens for shielding said device from said filter and from said last means.

'7. An oscillation generator system comprising an electron discharge device oscillator having an anode, a cathode, and a pair of grids, an oscillatory circuit between one of said grids and said anode, a connection from an intermediate point on said oscillatory circuit to said cathode, a source of low power constant frequency energy coupled to said other grid, means for maintaining said one grid at an average positive potential and said other grid at an average negative potential relative to said cathode, a resistance between each grid of said device and said cathode, and a load circuit coupled to said oscillatory circuit.

8. An oscillation generator system comprising a pentode electron discharge oscillator having an anode, a cathode, control, screen, and suppressor grids, a tuned oscillatory circuit coupled between said anode and suppressor grid, a connection from an intermediate point on said oscillatory circuit to said cathode, means for maintaining said screen and suppressor grids at a positive potential and said control grid at a negative potential relative to said cathode, a source of low power constant frequency energy coupled to said control grid, and a resistor between said control grid and said cathode.

9. An oscillation generator arrangement comprising an electron discharge device oscillator having an anode, a cathode, a control grid and a screen grid, means for maintaining said control grid at an average negative potential and said screen grid at an average positive potential relative to said cathode, an oscillatory circuit comprising a pair of inductance coils and a condenser in shunt of said coils, a connection from the junction point of said coils to said cathode, a capacitor connected between one plate of said condenser and said anode, and another capacitor connected between another plate of said condenser and said screen grid, an output circuit coupled to one of said coils, a pentode electron discharge device amplifier having an anode, a cathode, a control grid, a screen grid, and a suppressor grid, a capacitive path between said last anode and the control grid of said oscillator, a connection from said suppressor grid to the cathode of said pentode, a source of low power constant frequency oscillations coupled to the control grid of said pentode, and means for supplying a potential to said screen grid of said pentode which is positive with respect to its associated cathode.

10. A regenerative electron discharge device oscillation generation system comprising an electron discharge device oscillator having an anode, cathode, control grid and screen grid, means for maintaining said control grid at an average negative potential and said screen grid at an average positive potential relative to said cathode, a feedback path including an oscillation circuit extending from said anode to said screen grid, a connection from an intermediate point on said oscillation circuit to said cathode, a second electron discharge device oscillator having an anode, a cathode, a screen grid and a control grid, a piezo-electric crystal circuit coupled between said last anode and control grid, a capacitive connection from said last anode to the control grid of said first device, means for maintaining said last screen grid at a positive potential relative to its associated cathode, and a resistor connected between said last cathode and said capacitive connection.

DOUGLAS FRANK GEORGE. 

